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Research Description

The interests of my research group focus on the growth of narrow-gap semiconductors and device applications for these materials. We use molecular beam epitaxy to grow heterostructures for three research efforts: high-mobility and spin- dependent electron transport experiments, mid-infrared interband-cascade devices, and nanostructures for photovoltaic applications. Because the bandgap of InSb is the smallest of all binary III-V compounds, two-dimensional electron systems in InSb quantum wells have a small effective mass, a large g-factor, and strong spin-orbit effects. The room-temperature mobility in these structures is higher than in quantum wells made of any other semiconductor. We are exploring ways to exploit this and other features in devices based on ballistic transport and electron spin. Magneto-transport studies on these materials are being pursued with Sheena Murphy's group and external collaborators. In addition, we are working with Sheena Murphy's group on the search for new materials that exhibit topological-insulator behavior.

Our group also grows InAs/GaSb/AlSb structures for research on mid-infrared devices, including lasers and photodetectors, based on the interband-cascade architecture. This effort is led by Rui Yang in the electrical engineering department and also involves Matthew Johnson's group. Our group's newest effort is a collaboration with Ian Sellers' group and industrial collaborators on superlattice and quantum-dot structures for studying mechanisms that would enable third-generation photovoltaic devices.